Water Level Changes in Caspian Sea

The Caspian Sea is a landlocked sea between Asia and Europe. It is the world’s largest inland body of water, with a surface area of 371,000 km² (143,000 sq. mi.), and therefore has characteristics common to both seas and lakes.

The Caspian Sea is bordered by Russia (Dagestan, Kalmykia, Astrakhan Oblast), Republic of Azerbaijan, Iran (Guilan, Mazandaran and Golestan provinces), Turkmenistan, and Kazakhstan, with the central Asian steppes to the north and east. On its eastern Turkmen shore is a large embayment, the Kara Bogaz Gol (or Karabogas Bay), which here appears lighter blue in color by the right edge of the image.

The Volga River (about 80% of the inflow, visible in the upper left corner) and the Ural River (east of the former) discharge into the Caspian Sea, but it is endorheic, i.e. there is no natural outflow (other than by evaporation). Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world’s oceans. The level of the Caspian has fallen and risen, often rapidly, many times over the centuries.

Over the centuries, Caspian Sea levels have changed in synchronicity with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic Oscillation. Thus levels in the Caspian sea relate to atmospheric conditions in the North Atlantic thousands of miles to the north and west. These factors make the Caspian Sea a valuable place to study the causes and effects of global climate change.